Engineering of recombinant Escherichia coli cells co‐expressing poly‐γ‐glutamic acid (γ‐PGA) synthetase and glutamate racemase for differential yielding of γ‐PGA. Issue 6 (6th August 2013)

• Record Type: Journal Article
• Authors: Cao, Mingfeng; Geng, Weitao; Zhang, Wei; Sun, Jibin; Wang, Shufang; Feng, Jun; Zheng, Ping; Jiang, Anna; Song, Cunjiang
• Is Part Of: Microbial biotechnology. Volume 6:Issue 6(2013:Nov.)
• Page Start: 675
• Page End: 684
• Publication Date: 2013-08-06
• Subjects: Microbial biotechnology -- Periodicals; Biotechnology; Microbiology; 660.62
• DOI: 10.1111/1751-7915.12075
• Languages: English
• ISSNs: 1751-7915

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>Poly‐γ‐glutamic acid (γ‐PGA) is a promising environmental‐friendly material with outstanding water solubility, biocompatibility and degradability. However, it is tough to determine the relationship between functional synthetic enzyme and the strains' yield or substrate dependency. We cloned γ‐PGA synthetase genes <italic>pgsBCA</italic> and glutamate racemase gene <italic>racE</italic> from both L‐glutamate‐dependent γ‐PGA‐producing <italic>B</italic><italic>acillus licheniformis</italic> NK‐03 and L‐glutamate‐independent <italic>B</italic><italic>. amyloliquefaciens</italic> LL3 strains. The deduced RacE and PgsA from the two strains shared the identity of 84.5% and 78.53%, while PgsB and PgsC possessed greater similarity with 93.13% and 93.96%. The induced co‐expression of <italic>pgsBCA</italic> and <italic>racE</italic> showed that the engineered <italic>E</italic><italic>scherichia coli</italic> strains had the capacity of synthesizing γ‐PGA, and LL3 derived PgsBCA had higher catalytic activity and enhanced productivity than NK‐03 in Luria–Bertani medium containing glucose or L‐glutamate. However, the differential effect was weakened when providing sufficient immediateness L‐glutamate substrate, that is, the supply of substrate could be served as the ascendance upon γ‐PGA production. Furthermore, RacE integration could enhance γ‐PGA yield through improving the preferred <sc>d</sc>‐glutamate content. This is the first report about co‐expression of <italic>pgsBCA</italic> and <italic>racE</italic> from the two <italic>B</italic><italic>acillus</italic> strains, which will be of great value for the determination of the biosynthetic mechanism of γ‐PGA.</p> </abstract>